PDF (Preferred): Normally Editable Files, Large File Size, Good for Print

Ai or EPS: Illustrator Files, Editable in Most Situations

JPG or JPEG: Non-Editable, Low File Size, Good for Social Media Display Photos

PNG: Non-Editable, Low File Size, Good when Transparent Backgrounds are Needed like Advertisements and Websites

Pretty Much Everything, Aaron Draplin

Logo Mayhem Book, Lincoln Design Co.

Logo Modernism, Jens Müller and R. Roger Remington

Steal Like an Artist, Austin Kleon

Know Your Onions, Drew de Soto

Elements of Graphic Design, Alex W. White

Design Basics Index, Jim Krause

Logo Design Love, David Airey

Just My Type, Simon Garfield

Thinking with Type, Ellen Lupton

Burn Your Portfolio, Michael Janda

Freelance Business and Stuff, Hoodzpah

Building a Big Small Business Brand, Dan Antonelli

Buyology, Martin Lindstrom

Ephemera V2, Joshua Minnich